<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .main {
            width: 300px;
            height: 300px;
            background: skyblue;
            display: grid;
            grid-template-columns: repeat(3,1fr);
            grid-template-rows: repeat(3,1fr);
            gap: 5px;
        }
        .main div {
            background: red;
        }
        .main div:nth-of-type(1){
            grid-area: 1/1/span 2/ span 2;
        }
    </style>
</head>
<body>
    <div class="main">
        <div>1</div>
        <div>2</div>
        <div>3</div>
        <div>4</div>
        <div>5</div>
        <div>6</div>
    </div>
</body>
</html>